What is the reasoning behind not separating Sch and Smn stats?

[FMElan]

No, the biggest hinderance for end-game multi-classing is gear availability and advancement. If you want to complain about "having to choose," direct it towards gear lock-outs.

Almost everything in the game can be completed with i70 gear, which there's no lockout on.

Well, SMN could get Cleric Stance, but you'd have to give up either [Thunder, Swiftcast, and Surecast] or [Raging Strikes and Quelling Strikes] for [Aero, Cleric Stance, Protect, and Stoneskin].

...Okay, Summoners can't get Cleric Stance, because they can't equip Conjurer abilities. But you seem to already know that, so...what? Seriously, what's the point of this statement? That SE could change your secondary/tertiary classes?

...I guess they could...?

Yes, but the other 5 or 6 jobs don't have to suffer this balance issue, which is the point the OP is trying to make in case it was missed.

The other...wait, wait, wait. There are 9 Jobs. Two of them are tied to Arcanist. So there are 7, not 5 or 6. That's your first mistake.

The second mistake is...well, duh. Of course they don't have to "suffer this balance" issue, because they don't have secondary Jobs yet. Therefor, the path of progression is just Tank > Tank, DPS > DPS, Healer > Healer. In the future, they'll be adding in secondary Jobs for ALL of the classes, so that Gladiator can go Tank > DPS, and Conjurer can go Healer > DPS, or Lancer can go DPS > Tank.

Like the person you quoted said, Jobs are basically skill trees, or specializations. AFAIK, Most MMO's have used them to an extent, and it's something a lot of people have been asking for(customization in the Job department), this is just FFXIV's way of bringing that about. Instead of having a Paladin that can DPS, though, they might implement a Dark Knight as the DPS Spec for Gladiator.